2,2',2"-Nitrilo[triethyl-tris-(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2 '-diyl) phosphite] is a compound having the formula I ##STR1##
This compound of formula I is useful as a processing stabilizer for organic polymers as taught in U.S. Pat. Nos. 4,318,845 and 4,374,219. The compound of formula I is disclosed as being a white powder melting at 121.degree.-134.degree. C. The relatively high melting point of the "white powder" form of the compound of formula I as disclosed in the above mentioned patents is a problem when stabilizing organic polymers processed at relatively low temperatures such as blow molding of HDPE and processing of natural rubber. The result is the additive is not uniformly distributed within the organic polymer causing problems in the stabilization performance of the additive stabilizer.
In accordance with the present invention an amorphous form of the compound of formula I is obtained which does not suffer the problems associated with the higher melting powder reported previously. This new amorphous form is characterized by a glass transition temperature (T.sub.g) within the range of from 105.degree.-110.degree. C. free of any endothermic melting peak above 110.degree. C. up to 230.degree. C. as determined by differential scanning calorimetry (DSC). Additionally the amorphous form of the present invention gave a featureless X-ray diffraction pattern obtained using Cu-K.alpha..
The instant invention also relates to a process for the preparation of this novel amorphous solid modification of the compound of formula I.
The instant invention also pertains to a composition stabilized against thermal, oxidative and actinic induced degradation which comprises
(a) a polyolefin, and PA0 (b) an effective amount of the amorphous solid form of 2,2',2"-nitrilo[triethyl-tris-(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2, 2'-diyl)phosphite], characterized by melting in the range of 105.degree.-110.degree. C. and by an X-ray diffraction pattern which is featureless.
Preferably, the polyolefin is polypropylene.
The instant amorphous solid modification is obtained from any of the solid forms of the compound of formula (I) by melting the compound and rapidly cooling the melt. The preferred method consists of pouring the molten material onto a cool surface maintained below 100.degree. C., more preferably near 25.degree. C. The amorphous solid thus obtained may be further ground or granulated into any desired particle size by conventional means.
Differential scanning calorimetry (DSC) measurements are obtained on a TA Instrument Inc., 910 differential calorimeter, with a 100 mL/min nitrogen purge, aligned aluminum pan, temperature scan at 5.degree. C./min to 230.degree. C.
X-ray diffraction patterns are recorded on a Philip Norelco X-ray Diffractometer unit, using Cu-K.alpha. radiation with a nickel filter.